The use of radiation curable coating compositions based on unsaturated polyesters is limited by the rate of radiation cure and degree of radiation cure in air of known compositions containing unsaturated polyesters. For example, liquid films of known unsaturated polyesters cured with styrene typically require doses of 10 to 20 megarads of ionizing radiation (electron beam) for cure or, when cured using actinic radiation (ultraviolet light), cure at typical rates of from 5 to 10 feet/minute/lamp upon exposure to ultraviolet light (UV) from a medium pressure mercury vapor lamp operating at 200 watts/inch at a distance of about 4 inches from the surface of the wet film. Also such known compositions tend to exhibit disadvantages in surface curing characteristics.
The present invention is primarily directed to improving the radiation curing properties of liquid, compositions based on unsaturated polyester polymers and unsaturated polyester oligomers. Other objects of the invention will become apparent to the reader infra.